The health and hygiene benefits associated with regular and frequent hand washing have been understood throughout human history. Soap has been around for nearly as long as the benefits of washing have been understood. Through the years soap has evolved through many formulations and forms to meet the needs of the cleansing public.
Soap has been available in a bar form for most of its known existence. While a convenient form when placed near a water source in one's own dwelling, a bar of soap is not always convenient or sanitary outside the home. First, a bar of soap is not a very convenient form for a person to transport from place to place, especially when the bar is wet. Secondly, in a public setting, a bar of soap that is available for one and all to use can be unsanitary and uninviting for personal use.
One early solution dealing with the issue of soap sharing was the use of powdered soap dispensers in public restrooms and at communal washbasins within factories. Such dispensers allowed individuals to dispense appropriate amounts of the powdered soap to themselves. However, such soap was messy and left deposits of soap within washbasins. Additionally, the powdered soap needed to be contained and did not lend itself to easy transport if a person wished to take soap elsewhere.
Liquid soap is another soap form that solves the issue with sanitary individual soap use; the user need only dispense the amount of liquid soap that they wish to use themselves. However, such soap requires a dispenser in which to contain and to dispense the soap. Additionally, such soap is more expensive to distribute as a majority of the soap's weight is contributed by the water that makes up a large proportion of the liquid soap formulation.
More recently, soap has been available in a gel or a liquid/solid combination that eliminates much of the water that is used in liquid soaps. Such soaps ship as a solid, but have formulations that quickly lather with water. The gel soaps again allow for individual dispensing of soap, but they also require dispensers to contain and dispense the gel soap.